Preparation of methyl vinyl ketone from 3-ketobutan-1-ol

ABSTRACT

A process for obtaining methyl vinyl ketone by heating a solution comprising about 1 to 30 weight percent 3-ketobutan-1ol, about 0.005 to 0.50 weight percent of a strong acid, and one or more inert solvents.

United States Patent [1 1 Ember June 17, 1975 PREPARATION OF METHYL VINYL KETONE FROM 3-KETOBUTAN-l-OL [75] Inventor: George Ember, Hackensack, NJ.

[73] Assignee: Hoffmann-La Roche Inc., Nutley,

[22] Filed: June 25, 1973 [21] Appl. No.: 373,071

FOREIGN PATENTS OR APPLICATIONS 576,480 4/1946 United Kingdom OTHER PUBLICATIONS White et al., Journal of the Chemical Society, 1943, pp. 25-31 (1943).

Primary Examiner-Leon Zitver Assistant Examiner-James H. Reamer Attorney, Agent, or Firm-Samuel L. Welt; Jon S. Saxe; William H. Epstein [57] ABSTRACT A process for obtaining methyl vinyl ketone by heating a solution comprising about 1 to 30 weight percent 3-ketobutan-l-ol, about 0.005 to 0.50 weight percent of a strong acid, and one or more inert solvents.

10 Claims, No Drawings PREPARATION OF METHYL VINYL KETONE FROM 3-KETOBUTAN-1-OL BACKGROUND OF THE INVENTION This invention relates to the improved acidic dehydration of 3-ketobutan-l-ol to form methyl vinyl ketone.

Methyl vinyl ketone has heretofore been obtained by dehydrating 3-ketobutan-1-ol in the presence of a relatively concentrated, strong acid. See German Pat. No. 730,117, wherein N-sulfuric acid or N-hydrochloric acid utilized (about 5% by wt.), and White et al., Journal of the Chemical Society 1943: pp. 25-31 (1943), wherein 110% by weight of hydrochloric acid or phosphoric acid utilized.

Such dehydration processes utilizing relatively concentrated, strong acids have been found, however, to provide relatively low yields of methyl vinyl ketone, unless expensive and cumbersome reactive distillation procedures have also been utilized. For this reason, the dehydration of ketobutanol, utilizing relatively high acid concentrations, has had to be carried out in a semi-continuous fashion, with the methyl vinyl ketone being immediately distilled-off as it is formed in the reaction mixture. Hence, it has not been practical to carry out the acid dehydration of ketobutanol in an efficient, continuous manner.

SUMMARY OF THE INVENTION In accordance with the process of this invention, methyl vinyl ketone is obtained by heating a solution comprising about 1 to 30 weight percent 3-ketobutanl-ol, about 0.005 to 0.50 weight percent of a strong acid and about 70 to 99 weight percent of an inert solvent. By this process, improved yields of methyl vinyl ketone are obtained without the need for continuously removing the methyl vinyl ketone from the solution as soon as it is formed.

DETAILED DESCRIPTION OF THE INVENTION By the process of this invention, methyl vinyl ketone is obtained byheating a solution comprising 1 to 30 weight percent 3-ketobutan-l-ol, 0.005 to 0.50 weight percent of a strong acid and 70 to 99 weight percent of an inert solvent. In this process, the weight percents of the acid, the 3-ketobutan-l-ol and the inert solvent are based on the entire solution containing these materials.

In the process of this invention, the solution containing the 3-ketobutan-l-ol and the strong acid also contains one or more inert solvents as diluents. In this process, any conventional, inert solvent in which the 3- ketobutan-l-ol and the strong acid are soluble can be utilized. Among the inert solvents which can be utilized, either individually or in a mixture of solvents, are water; the lower alkanols, such as methanol, ethanol and isopropanol; ketones such as acetone, methyl ethyl ketone, tetrahydrofuran and dioxane; and the chlorinated hydrocarbons, such as tetrachloroethane, trichloroethylene and chlorobenzene. Preferably, a mixture of inert solvents comprising about 0 to about'60% water and 40 to 100% of one or more inert, water soluble, or-

ganic solvents is utilized, particularly a mixture of inert solvents which contains about to 45% water. Especially preferred is a mixture of inert solvents consisting essentially of about 55 to 90% acetone and about 10 to 45% water.

In this process, the inert solvent can also contain trace or larger amounts of various other diluents, such as diacetone alcohol and mesityl oxide, as well as traces of materials, such as formaldehyde, which do not significantly affect the acid dehydration of 3-ketobutan-l-ol to methyl vinyl ketone. However, in the solution containing the acid and the 3-ketobutan-l-ol which is reacted to form methyl vinyl ketone, the inert solvent of the process of this invention comprises about to 99%. Preferably, the inert solvent comprises about to of the solution containing the 3-ketobutan-l-ol and the acid.

In carrying out the process of this invention, any conventional strong acid having a dissociation constant (in water at 25C.) of greater than about 10* can be utilized. Among the preferred strong acids which can be utilized are the mineral acids, such as sulfuric acid, sulfurous acid, hydrochloric acid, perchloric acid, hydrobromic acid and phosphoric acid, and the strong organic acids, such as formic acid, oxalic acid, trichloroacetic acid and the sulfonic acids, such as the toluene sulfonic acids, particularly paratoluene sulfonic acid, the lower alkyl sulfonic acids, particularly methyl sulfonic acid, and the nitrophenyl sulfonic acids, particularly p-nitrophenyl sulfonic acid. Among the foregoing strong acids, especially preferred for use in the process of this invention are sulfuric acid, phosphoric acid and the sulfonic acids, particularly paratoluene sulfonic acid.

In this process, the amounts of strong acid and 3- ketobutan-l-ol utilized respectively comprise between about 0.005 and 0.50% and l to 30% of the solution containing these reactants. It is preferred that the acid be present in an amount between about 0.02 and 0.20% of the reaction mixture. A particular preferred amount of acid is between about 0.05 and 0.1%. It is also preferred that the 3-ketobutan-l-ol be present in an amount greater than 5%, particularly in an amount between about 10 to 20%.

In carrying out the process of this invention, temperatures of about C, to about 300C. can be utilized, with temperatures of C. to 260C. being preferred, particularly temperatures of C. to 220C. In this process, any pressure at or above the vapor pressure of the reaction mixture at the temperature of the reaction mixture can be utilized. Under the preferred conditions of the process of this invention, pressures of about 300 p.s.i.a. to about 800 p.s.i.a. are generally utilized. However, in this process, greater pressures can also be utilized, such as a pressure of up to approximately 7000 p.s.i.a., as well as lower pressures of down to approximately 30 p.s.i.a.

The methyl vinyl ketone produced by the process of this invention can be suitably isolated from the reaction mixture in a conventional manner. It can be isolated by fractional distillation and/0r extraction of the reaction mixture which results when the process of this invention is carried out in a homogeneous system, i.e., with one liquid phase. For example, the methyl vinyl ketone can be isolated by heating the solution, containing the methyl vinyl ketone, to its boiling point to produce a distillate containing principally water and methyl vinyl ketone. The methyl vinyl ketone can then be conveniently extracted from the water in a conventional manner, such as by treating the distillate with pentane.

By the liquid phase process of this invention, yields of up to about 98% methyl vinyl ketone, based on ketobutanol, can be expeditiously obtained with virtually complete consumption of ketobutanol. In addition, the reaction rate of this process is relatively high, resulting in relatively large outputs of methyl vinyl ketone with conventional, liquid phase processing equipment. In fact, reaction times of less than one hour, preferably to minutes, can be utilized for the reaction to go to completion. Furthermore, where acetone is utilized as in inert solvent in this process, the mixture of 3- ketobutan-l-ol and acetone, which is conventionally produced by the reaction of acetone and formaldehyde, can be utilized directly as the starting material in this process, without having to remove the acetone therefrom.

Also by this process, the aforementioned advantages in yields of methyl vinyl ketone, consumption of ketobutanol, reaction rates, and formulations of starting materials can be expeditiously achieved without the necessity of utilizing reactive distillation procedures. Therefore, this application affords an advantageous procedure for the acidic dehydration of ketobutanol whereby methyl vinyl ketone can be efficiently produced in a continuous manner.

The examples which follow illustrate the process of this invention.

EXAMPLE 1 Table 1 Feed Effluent wt.% wt.%

Sulfuric acid 0.1 0.1 Acetone 81.37 80.2 Ketobutanol 14.36 0.6 Methyl vinyl ketone 0.76 11.7 Water 0.75 4.23 Other materials* 2.65 3.2

The principal. other material in the feed is diacetone alcohol and in the effluent is mcsityl oxide for each example.

The average yield of methyl vinyl ketone over several runs using the above procedure was about 96 i 2%, with 96% conversion of ketobutanol.

EXAMPLE 2 Utilizing the procedure of Example 1, a mixture containing 3-ketobutan-1-ol, acetone and sulfuric acid was charged into a bomb, and the bomb was immersed in an oil bath at 202C. for 6 minutes. The results, as analyzed by gas chromatography, are summarized below in Table 2.

The average yield of methyl vinyl ketone over several runs using the above procedure was about 97 i 2%, with about 95.6% conversion of ketobutanol EXAMPLE 3 Utilizing the procedure of Example 1, a mixture containing 3-ketobutanol, acetone and sulfuric acid was charged into a bomb, and the bomb was immersed in an oil bath at 164C. for 20 minutes. The results, as analyzed by gas chromatography, are summarized below inTable 3.

Table 3 Feed Effluent wt.% wt.%

Sulfuric acid 0.05 0.05 Acetone 80.95 80.86 Ketobutanol 12.21 0.55 Methyl vinyl ketone 2.47 1 1.68 Water 1.46 3.8 Other materials 2.90 3.06

The average yield of methyl vinyl ketone over several runs using the above procedure was about 96 i 2% with about 96.5% conversion of ketobutanol.

EXAMPLE 4 Utilizing the procedure of Example 1, a mixture containing 3-ketobutan-l-ol, acetone and paratoluenesulfonic acid was charged into a bomb, and the bomb was immersed in an oil bath at 202C. for 20 minutes. The results, as analyzed by gas chromatography, are summarized below in Table 4.

Table 4 Feed Effluent wt.% wt.%

Paratoluene sulfonic acid 0.07 0.07 Acetone 77.32 76.5 Ketobutanol 14.7 0.42 Methyl vinyl ketone 1.48 10.1 Water 1.0 4.25 Other materials 5.45 8.7

The yield of methyl vinyl ketone was about with about 97.2% conversion of ketobutanol.

EXAMPLE 5 Utilizing the procedure of Example 1, test mixtures containing 3-ketobutan-l -ol and acetone were formulated with and without phosphoric acid. Each test was charged into a bomb, and the bomb was immersed in an oil bath at 200C. for 15 minutes. The results, as analyzed by gas chromatography, are summarized below in Table 5.

Table 5 Test with Phosphoric Acid Test without Phosphoric Acid wt.% wt.% wt.% wt.%

Phosphoric acid 0.05 0.05 Phosphoric acid 0 Acetone 79.0 79.5 Acetone 79.0 80.2 Ketobutanol 14.4 7.2 Ketobutanol 14.4 10.8 Methyl vinyl ketone 1.7 7.16 Methyl vinyl ketone 1.7 3.6 Water L0 236 Water 1.0 1.5 Other materials 3.9 3.77 Other materials 3.9 3.8

The yield of methyl vinyl ketone was about 95 The yield of methyl vinyl ketone was about i 3% with about 50% conversion of ketobutanol. ketobutanol.

EXAMPLE 6 Utilizing the procedure of Example 1, a mixture containing 3-ketobutan-l-ol, acetone and sulfuric acid was charged into a bomb. The bomb was rapidly heated (by immersion in a hot oil bath) to 200C., held at this temperature for min., and then quenched. The results, as analyzed by gas chromatography, are summarized below in Table 6.

The yield of methyl vinyl ketone was about 89.8%, with about 81.6% conversion of ketobutanol.

I claim:

l. A process for obtaining methyl vinyl ketone, comprising heating, at a temperature of 100C. to 300C. and at a pressure at or above the vapor pressure of the reaction mixture, a solution comprising about 1 to 30 65% with about 25% conversion of weight percent 3-ketobutan-l-ol, about 0.005 to 0.50 weight percent of sulfuric acid, and about to 99 weight percent of an inert solvent.

2. The process of claim 1 wherein said process is carried out at l20260C.

3. The process of claim 2 wherein said process is carried out at 150C. to'220C.

4. The process of claim 1 wherein 3-ketobutanol-1-ol comprises greater than 5 weight percent of said solution.

5. The process of claim 4 wherein 3-ketobutan-l-ol comprises about 10 to 20 weight percent of said solution.

6. The process of claim 1 wherein said acid comprises about 0.02 to 0.20 weight percent of said solution.

7. The process of claim 6 wherein said acid comprises about 0.05 to 0.1 weight percent of said solution.

8. The process of claim 1 wherein said inert solvent comprises about 0 to 60 weight percent water and about 40 to 100 weight percent of an inert organic solvent.

9. The process of claim 8 wherein said inert solvent comprises 10 to 45 weight percent water.

10. The process of claim 9 wherein said inert solvent comprises about 55 to weight percent acetone and about 10 to 45 weight percent water. 

1. A PROCESS FOR ABTAINING METHYL VINYL KETONE, COMPRISING HEATING, AT A TEMPERATURE OF 100*C. TO 300:C AND AT A PRESSURE AT OR ABOVE THE VAPOR PRESSURE OF THE REACTION MIXTURE, A SOLUTION COMPRISING ABOUT 1 TO 30 WEIGHT PERCENT 3KETOBUTAN-1, ABOUT 0.005 RO 0.50 WEIGHT PERCENT OF SULFURIC ACID, AND ABOUT 70 TO 99 PERCENT OF AN INERT SOLVENT.
 2. The process of claim 1 wherein said process is carried out at 120*-260*C.
 3. The process of claim 2 wherein said process is carried out at 150*C. to 220*C.
 4. The process of claim 1 wherein 3-ketobutanol-1-ol comprises greater than 5 weight percent of said solution.
 5. The process of claim 4 wherein 3-ketobutan-1-ol comprises about 10 to 20 weight percent of said solution.
 6. The process of claim 1 wherein said acid comprises about 0.02 to 0.20 weight percent of said solution.
 7. The process of claim 6 wherein said acid comprises about 0.05 to 0.1 weight percent of said solution.
 8. The process of claim 1 wherein said inert solvent comprises about 0 to 60 weight percent water and about 40 to 100 weight percent of an inert organic solvent.
 9. The process of claim 8 wherein said inert solvent comprises 10 to 45 weight percent water.
 10. The process of claim 9 wherein said inert solvent comprises about 55 to 90 weight percent acetone and about 10 to 45 weight percent water. 